such as cranks, rods, etc? thanks,

dk

 

cranks most times yes... some rods like a H beam no, because they are fully machined forgings which are actually stronger anyways.

Bret

 

I don't know if this is always the case, but the forging line was clearly visible on my Cola crankshaft (see arrows) and my Crower billet ultralight had none.

http://home.gci.net/~jimlab/images/Misc/crankshafts.jpg

 

That one on the left is beautiful!

 

thanks for the pics, it shows a very good comparison. I have seen the casting lines on "cast" products but i didn't know that forgings left the same.

dk

 

I'm not sure about the billet vs forged issued but as for the statement above, cast vs. forged, they both have a parting line. On the end of the counterweight, the one on a cast crank is a thin line and the one for a forged crank is a wide line.

 

The Cola forged crank in the pic appears to be a "twisted" forging. It's forged in one (two-piece) die as a "flat" or 180* crank, and then the two middle throws are twisted 90* while the forging is still hot.

A non-twisted forging is formed in a couple of dies. One does the nose and rear flange and the outer throws, and the other does the inner part. The forging is turned 90* when moved from one die to the next.

Some folks think non-twsted forgings are stronger. They are usually more costly.

 

Ok, you have me confussed, not hard to do. In the pic. of the Crower "billet" crank there is a very distinct "cast" line that can be seen on the last rod throw. I thought billet ment the item was totally machined from a solid piece of material?

 

You're evidently seeing something that I'm not. Are you sure it isn't just the reflection off the machined surface?

It does. In this case, a ~350 lb. billet of 4340 chromemoly, which is one of the reasons the cost is so high.